It is old to provide spirally wound wire layers in the walls of tubes formed of cured resins as represented by the patents to Meissner, U.S. Pat. No. 2,609,002, Sept. 2, 1952 and to Champleboux et al, U.S. Pat. No. 3,766,949, Oct. 23, 1973.
The Meissner patent shows rather widely spaced spring support wire in a thin walled hose stucture that deforms when the hose is bent so that a portion of the peripheral wall of the hose flexes inwardly in the form of a bead while the outer wall is stretched taut. The wire spring coils are deformed so that on the periphery of the casing around the inner radius of the bent pipe, the wires move more closely together and the wires move apart somewhat as the casing stretches around the outer periphery of the bend.
The Champleboux et al patent shows a hose designed to withstand substantial external pressures wherein differences in pressure of about 6 or 7 bars between the internal passageway and the external wall of the hose can be sustained in a cylindrical hose without any appreciable crushing of the hose. The structure is not described as being adapted, however, to contain substantial internal pressures, it being stated that it should be used where such pressure is equal to or less than 2 bars. Reenforcing wires or rings are built into the wall of the hose to sustain the pressure applied inwardly against the periphery of the hose. If the hose is to be bent, a special corrugated design is required, having cylindrical zones joined by bellows forming zones that may extend either inwardly or outwardly from the internal and external walls of the hose.